The qualified glucose after the batching and elimination system, enters the fermentation system to maintain a certain time of fermentation, then goes into the filtration removal system to remove the coarse protein. After the fermentation broth is concentrated, it enters the acidolysis system of calcium lactate. After filtering CaSO4, it goes through the continuous isolation system for decolorization, deodorization and desalting. After refining, it enters the membrane filtration system, concentration and purification system to obtain the qualified L-lactic acid product.